The pulsing is the stepper motor, or, may also be due to the ECU constantly changing the ignition advance by large amounts, or , a combination of both, all to try and keep the idle speed at 850.
Things to check and replace in this order
Calibrate (Index) the throttle and cable
Check all the thin black red and yellow vacuum lines, particularly the two that come off the back of the manifold. These have a habit of splitting. ensure there is no chance of a leak. * EDIT (Make sure you check the ones on the charcoal canister under the right wing)This is on carb models and does not apply to the SPi *. Ensure there is no fuel or oil in the lines to the ECU, blow them through. Infact, dont check the fittings/ elbows on the back of the manifold, replace them. :cheese:
Check all breather lines are clear and no leaks, agian check the charcoal canister.
Change the Lambda sensor
Change the fuel filter
Other common faults that can exist are faulty stepper motor, Shorted out PTC heater, Duff MAP sensor in the ECU. Check those above first as going deeper requires a Diagnostic unit like the one i've got
http://cgi.ebay.co.u...1QQcmdZViewItem This is the most basic of basic tools but the most affordable
